Circuit Description
The pressure switch manifold (PSM) is a multiple-switch assembly made up of three normally open (N/O) pressure switches and one normally closed (N/C) pressure switch for reverse pressure. Fluid pressure is supplied to the reverse pressure switch when the manual selector valve is in any position except REVERSE. When the manual selector valve is moved to REVERSE, pressure to the reverse pressure switch is cut off causing the switch to close.
DTC P0875 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0875 Reverse Pressure Switch Circuit Malfunction
Conditions for Running the DTC
| • | The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts. |
| • | Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds. |
| • | The park/neutral position (PNP) switch is enabled and functional. |
| • | Transmission fluid temperature (TFT) is greater than 0°C (32°F). |
| • | DTCs P0708 and P1714 are not active. |
Conditions for Setting the DTC
DTC P0875 sets when PARK, NEUTRAL, or a forward range is selected and the reverse pressure switch remains in the mechanically closed/electrically on position for a period of time that is calibration dependent.
Action Taken When the DTC Sets
| • | The transmission control module (TCM) will illuminate the malfunction indicator lamp (MIL). |
| • | The transmission will lock in NEUTRAL. |
| • | DTC P0875 will be stored in TCM history. |
| • | The TCM freezes shift adapts. |
| • | The TCM inhibits torque converter clutch (TCC) engagement. |
Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
| • | Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions: |
| - | A bent terminal |
| - | A backed-out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | You may have to drive the vehicle in order to experience a condition. |
| • | This DTC could indicate a hydraulic leak path exhausting pressure from the reverse pressure switch. |
| • | An inactive DTC P0875 set in combination with DTC P0872 often indicates that an internal PNP switch failure occurred on a previous drive cycle. If this combination returns after clearing the DTCs, replacement of the PNP switch may be necessary. |
| • | The intent of this code is to detect discrepancies between the range selected at the PNP and the actual position of the manual selector valve. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the TCM response function.
-
This step tests the transmission wiring harness integrity.
-
This step tests and evaluates the internal wiring harness.
-
This step tests the PSM for a failed condition.
Step | Action | Value | Yes | No |
|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 | Measure the transmission fluid level. Refer to Transmission Fluid Check . Is the transmission fluid level correct? | -- | Go to Step 3 | Go to Transmission Fluid Check |
3 | Measure line pressure. Refer to Line Pressure Check . Is the line pressure within the specified value? | -- | Go to Step 4 | |
4 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Does the scan tool indicate TFP SW. R status is OFF? | -- | Go to Diagnostic Aids | Go to Step 5 |
Does the scan tool indicate TFP SW. R status is ON when grounded and OFF when open? | -- | Go to Step 6 | Go to Step 12 | |
Does the scan tool indicate TFP SW. R status is ON when grounded and OFF when open? | -- | Go to Step 7 | Go to Step 11 | |
Does the scan tool indicate TFP SW. R status is ON when grounded and OFF when open? | -- | Go to Step 8 | Go to Step 10 | |
Does the scan tool indicate TFP SW. R status is ON when grounded and OFF when open? | -- | Go to Diagnostic Aids | Go to Step 9 | |
9 | Replace the PSM. Refer to Pressure Switch Manifold Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
10 | Replace the internal wiring harness. Refer to Wiring Harness Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
11 | Repair the engine wiring harness circuit for an open or short. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 13 | -- |
12 |
Important: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM. Replace the TCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 13 | -- |
13 | Perform the following procedure in order to verify the repair:
Has test run and passed? | -- | System OK | Go to Step 1 |
